Stomatal response to drying soil in relation to changes in the xylem sap composition of Helianthus annuus. II. Stomatal sensitivity to abscisic acid imported from the xylem sap

Authors

  • U. SCHURR,

    Corresponding author
    1. Lehrstuhl für Pflanzenökologie, Universität Bayreuth, Postfach 10 12 51, 8580 Bayreuth, Germany
      and present address: V. Schurr, Botanisches Institut, Universitat Heidelberg, Im Neuenheimer Feld 360, 6900 Heidelberg, Germany.
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  • T. GOLLAN,

    1. Lehrstuhl für Pflanzenökologie, Universität Bayreuth, Postfach 10 12 51, 8580 Bayreuth, Germany
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  • E.-D. SCHULZE

    1. Lehrstuhl für Pflanzenökologie, Universität Bayreuth, Postfach 10 12 51, 8580 Bayreuth, Germany
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and present address: V. Schurr, Botanisches Institut, Universitat Heidelberg, Im Neuenheimer Feld 360, 6900 Heidelberg, Germany.

ABSTRACT

Sunflower plants [Helianthus annuus L.) were subjected to soil drought. Leaf conductance declined with soil water content even when the shoot was kept turgid throughout the drying period. The concentration of abscisic acid in the xylem sap increased with decreasing soil water content. No general relation could be established between abscisic acid concentration in the xylem sap and leaf conductance due to marked differences in the sensitivity of leaf conductance of individual plants to abscisic acid from the xylem sap. The combination of these results with data from Gollan, Schurr & Schulze (1992, see pp. 551–559, this issue) reveals close connection of the effectiveness of abscisic acid as a root to shoot signal to the nutritional status of the plant.

Ancillary